1. Field of the Invention
The present invention relates to A semiconductor apparatus and a method of producing the same, more particularly, relates to a compound film containing nitrogen (for example, a TiN film) used for example as a barrier film in a contact portion between an interconnection layer and a semiconductor or a contact portion between one interconnection layer and another interconnection layer.
2. Description of the Related Art
The increasing miniaturization of semiconductor devices has led to greater demands on the reliability of interconnections. Particularly, the metal using for forming a film so as to give an ohmic-contact with respect to a shallow junction of a transistor and the underlying silicon (Si) are brought into close contact by a boundary reaction so as to give a good electrical connection. If the reaction is excessively advanced, however, the metal penetrates through the shallow junction portion to cause a large junction leakage. Conversely, if the reaction is insufficient, there is a problem in that the ohmic-contact is not obtained and therefore the electrical characteristics become unstable.
Here, an example of a process for producing a conventional metal oxide semiconductor (MOS) large-scale integrated circuit (LSI) will be explained with reference to FIGS. 1A to 1C.
(a) As shown in FIG. 1A, an element isolation region (LOCOS) 4, a gate insulation film 6, a gate electrode 8. and a source-drain region 10 are formed on the surface of a semiconductor substrate 2 to form an MOS transistor.
(b) Next, as shown in FIG. 1B, an interlayer insulation film 12 is formed on the MOS transistor, and a contact hole 14 is formed in this.
(c) Next, as shown in FIG. 1C, blanket tungsten 16 or the like is filled in the contact hole 14. Further, a film of an aluminum (Al)-based alloy 17 such as Al--Si is formed on this and subjected to patterning so as to form an interconnection region.
While the element is formed by the example of the production process described in the above steps (a) to (c), the interconnections and the silicon substrate (Si) have been connected using a laminate structure of silicon nitride and titanium (TiN/Ti). However, if the reaction of the Ti is insufficient, a good ohmic-contact is not obtained and a problem occurs.
As a method of keeping the reaction between the interconnection metal and the underlying silicon from being obstructed, use has been made of a TiN film. By forming a TiN film with a good barrier property, the contact characteristics can be stabilized. However, it has been not been possible to control the change in the film quality with respect to the parameters of the method of forming the TiN film. Therefore, at the present time, it is not possible to produce a device with the best film quality.
Also, recently, a technique of forming a film of TiN by collimate sputtering has been developed. Collimate sputtering is a technique where a collimate is disposed between the target of the sputtering apparatus and the wafer and sputtering particles of an oblique direction are made to deposit on it, whereby only particles in the vertical direction and in directions close to this are taken out, thereby improving the bottom coverage rate of the contact holes.
In this collimate sputtering, generally, the flow rate of the nitrogen gas with respect to the argon gas was as high as 1.5 or more. Also, in this collimate sputtering, it was impossible to control the changes in the film quality with respect to the parameters of the method of forming the TiN film. Therefore, at the present time, it is not possible to prepare a device with the best film quality.